如何在代码创建的UIView中添加同样以代码方式生成的UITextView

想要制作类似Instagram和Snapchat的文本接收视图，尝试在代码创建的UIView中同样用代码添加UITextView，现有代码组合运行后无法达到预期效果。

当前运行效果：

预期实现效果：

原始问题代码 #

import UIKit

class TextViewViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let View1: UIView = {
            let viewView = UIView()
            viewView.translatesAutoresizingMaskIntoConstraints = false
            viewView.contentMode = .scaleAspectFit
            viewView.backgroundColor = .red
            viewView.clipsToBounds = true
            return viewView
        }()

        self.view.addSubview(View1)

        View1.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: 0).isActive = true
        View1.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 0).isActive = true
        View1.topAnchor.constraint(equalTo: view.topAnchor, constant: 250).isActive = true
        View1.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -250).isActive = true
        
        let textView = UITextView(frame: CGRect(x: 20.0, y: 90.0, width: 250.0, height: 100.0))
        textView.contentInsetAdjustmentBehavior = .automatic
         
         textView.center = self.view.center
         textView.textAlignment = NSTextAlignment.justified
         textView.backgroundColor = UIColor.lightGray
         
         // Use RGB colour
         textView.backgroundColor = UIColor(red: 39/255, green: 53/255, blue: 182/255, alpha: 1)
         
         // Update UITextView font size and colour
         textView.font = UIFont.systemFont(ofSize: 20)
         textView.textColor = UIColor.white
         textView.font = UIFont(name: "Verdana", size: 17)

         // Make UITextView web links clickable
         textView.isSelectable = true
         textView.isEditable = false
         textView.dataDetectorTypes = UIDataDetectorTypes.link
         
         // Make UITextView corners rounded
         textView.layer.cornerRadius = 10

         // Make UITextView Editable
         textView.isEditable = true
        View1.addSubview(textView)
//
//        let textView: UITextView = {
//            let tv = UITextView(frame: CGRect(x: 20.0, y: 90.0, width: 100.0, height: 50.0))
//            tv.contentInsetAdjustmentBehavior = .automatic
//            tv.center = self.view.center
//            tv.textAlignment = NSTextAlignment.justified
//            tv.textColor = UIColor.blue
//            tv.backgroundColor = UIColor.lightGray
//            return tv
//        }()
//
//        View1.addSubview(textView)
        
//        textView.topAnchor.constraint(equalTo: View1.topAnchor, constant: 20).isActive = true
//        textView.bottomAnchor.constraint(equalTo: View1.bottomAnchor, constant: 20).isActive = true
//        textView.leadingAnchor.constraint(equalTo: View1.leadingAnchor, constant: 0).isActive = true
//        textView.trailingAnchor.constraint(equalTo: View1.trailingAnchor, constant: 0).isActive = true
    }
}

代码存在两个核心问题：

• 没有给UITextView设置translatesAutoresizingMaskIntoConstraints = false，手动设置的frame、center和自动布局约束冲突，导致约束不生效
• 注释的约束代码中，底部约束常量错误，应该为负值才会向内缩进，否则textView底部会超出父视图边界

修正后完整代码 #

import UIKit

class TextViewViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let containerView: UIView = {
            let view = UIView()
            view.translatesAutoresizingMaskIntoConstraints = false
            view.backgroundColor = .red
            view.clipsToBounds = true
            return view
        }()

        self.view.addSubview(containerView)

        NSLayoutConstraint.activate([
            containerView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            containerView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            containerView.topAnchor.constraint(equalTo: view.topAnchor, constant: 250),
            containerView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -250)
        ])
        
        let textView = UITextView()
        // 核心配置：禁用自动转frame为约束
        textView.translatesAutoresizingMaskIntoConstraints = false
        textView.contentInsetAdjustmentBehavior = .automatic
        textView.textAlignment = .justified
        textView.backgroundColor = UIColor(red: 39/255, green: 53/255, blue: 182/255, alpha: 1)
        textView.font = UIFont(name: "Verdana", size: 17)
        textView.textColor = .white
        textView.isSelectable = true
        textView.isEditable = true
        textView.dataDetectorTypes = .link
        textView.layer.cornerRadius = 10

        containerView.addSubview(textView)
        
        // 激活textView约束，上下左右相对于containerView缩进20
        NSLayoutConstraint.activate([
            textView.topAnchor.constraint(equalTo: containerView.topAnchor, constant: 20),
            textView.bottomAnchor.constraint(equalTo: containerView.bottomAnchor, constant: -20),
            textView.leadingAnchor.constraint(equalTo: containerView.leadingAnchor, constant: 20),
            textView.trailingAnchor.constraint(equalTo: containerView.trailingAnchor, constant: -20)
        ])
    }
}

内容的提问来源于stack exchange，提问作者iosDevSan